Haskell Weekly


Issue 299 2022-01-20

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Welcome to another issue of Haskell Weekly! Haskell is a safe, purely functional programming language with a fast, concurrent runtime. This is a weekly summary of what’s going on in its community.


  • What skills will give you an edge in 2022? (ad)

    Take the Developer Nation survey and share your views about the most important coding skills, tools, and platforms for 2022. You will get a virtual goody bag with free resources, plus a chance to win an iPhone 13, a Nintendo Switch, licenses, Amazon vouchers and more.

  • Haskell series part 9 by Pierre Guillemot

    This is the ninth article of a series on the functional language Haskell for beginners. In this article we discover modules and exceptions.

  • About that Reader trick by Micah Cantor

    This makes Reader a bad abstraction for modeling variable binding in, say, the Scheme programming language, which crucially has both of these (define for global variables and set! for mutation).

  • Abstracting over Branch and Bound

    What is the optimal Wordle strategy? We can figure this out with Branch and Bound (BnB). BnB describes a class of algorithms I hadn’t heard of for the longest time, probably because the literature tends to be really vague.

  • Beyond Typeclassopedia by Felix Springer

    This article is mainly an overview and doesn’t try to explain each type class. I also want to point out some opinionated critique.

  • Enumerate Wordle combinations with an applicative functor by Mark Seemann

    To be clear, this article isn’t really about Wordle strategies or tools. Rather, it’s an example of ad-hoc programming. Particularly, it’s an example of how the applicative nature of lists can be useful when you need to enumerate combinations.

  • Episode 1: Jonathan Lorimer by Cofree Coffee

    In which Jonathan Lorimer discusses getting into programming as an adult, hiring a programming coach, building communities, mentorship, data vs codata, the use of philosophy in the modern world, and the importance of taking yourself seriously.

  • How Long is your List? by Jack Kelly

    In Haskell, it’s often not practical or ergonomic to track exact lengths of lists at the type level. Let’s instead reflect on some ancient wisdom, and think about lists that have at {least,most} {zero,one,infinitiely many} elements.

  • Typed Template Haskell in GHC 9 by Heitor Toledo Lassarote de Paula

    Today we will take a look at the changes that were made in GHC 9 regarding typed Template Haskell (TTH) and how to use the th-compat library to write TTH code that will work with both GHC 8 and GHC 9.

  • Why Liquid Haskell Matters by Facundo Domínguez

    The conjecture that I pose is that many of the properties that would usually require dependent types to ensure at compile time, can be described in Liquid Haskell specifications.


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In brief

  • Haskell Official Docker Images now support arm64 by Alistair Burrowes

    I am happy to announce that as of versions 8.10.7, 9.0.2 and 9.2.1 the official Debian images support arm64.

  • NixOS: The Ultimate Dev Environment? by Martin Myrseth

    What got me motivated into writing this post is that once all the pieces came into place the resulting development workflow turned out to be quite amazing.

  • Transposing Rows by Monday Morning Haskell

    The transpose function takes a list of lists, which we can think of as a “matrix”. Then it transposes the matrix so that the rows are now the columns.

  • TypeVille conference

    Join the Scalar descendant, a 3-day conference full of programming and fun! We’re opening the event to other strongly typed languages: Java, Haskell, Kotlin, Rust and TypeScript, while Scala remains a focal point of the event & our TypeVille community. [Editor’s note: Use promo code typeville_loves_haskellweekly for 10% off. First come first served.]

Show & tell

  • Haskell Spotlight by Kiryl Valkovich

    New browser extension to search over Hoogle and Hackage.

  • SPADE by Sandeep Chandrika

    A simple weakly typed, dynamic, interpreted programming langauge and terminal IDE.

  • WebGear by Raghu Kaippully

    Webgear is a framework to build HTTP APIs in Haskell. WebGear helps to run these APIs as a web application, automatically generate OpenAPI documentation, and extract other static information about the APIs in general.

Call for participation